A new computer-aided system will be developed for the serial section reconstruction of the nematode nervous system from electron micrographs. By enabling fast and accurate reconstructions, this system will make it possible to compare the exact wiring of individual animals, at different stages of development, between the two sexes, and in behavioral mutants from this model organism. New techniques and methods will be designed and tested for the handling of all data in digital format subsequent to electron microscopy. Digitized data will allow development of computer assisted approaches to marking cell profiles in electron microscopic images and reconstructing the cell shapes, synaptic relationships, and complete wiring diagrams. Three dimensional information on axon position, axon size, trajectory, and synaptic relationships will be stored in a SAS dataset for each traced neuron from sectional data. This will allow the conversion and display of sectional data into 3D rendered objects for comparison with GFP-labeled cells. Raw data and processed 3D data will be shared with the C. elegans community on a website and on CDs. The project will be coordinated at the Center for C. elegans Anatomy, an NCRR-funded resource which provides TEM expertise to the community. The synaptic wiring of the 100 neurons of the adult male tail, including the preanal ganglion and the lumbar ganglia, will be compared in two animals in serial sections, as well as through comparisons with GFP-labeled neurons. This portion of the nematode nervous system has never been adequately reconstructed previously. The preanal ganglion circuitry provides a unique opportunity to explore the development and function of a defined set of synapses during postembryonic life in a system which is not essential for survival in this hermaphroditic species.